The San Antonio Water System is soliciting bids for sodium hydroxide (both 25% and 50 %) that is ANSI/NSF standard 60 Certified, delivered in bulk to Twin Oaks Plant’s Desal Bulk Tanks at 4588 Hardy Rd, Elmendorf, Texas 78112. SAWS will require a combination of both concentrations since 50% freezes at about 55oF. SAWS will use 50% when temperatures are warm and 25% when they are cooler.